Water

PG&E is committed to using water responsibly in our operations and at our facilities—and to helping our customers do the same.

Our approach

Water is essential to operating our infrastructure—including our vast network of hydroelectric generating stations—just as it is essential to our customers in their daily lives. PG&E is promoting sustainable water use in a number of ways:

• Strategically managing our power generation facilities.
• Reducing water consumption at PG&E offices and service centers.
• Providing outreach and guidance to customers on how to reduce water usage.

Power generation

At our Diablo Canyon Power Plant, we use saltwater from the Pacific Ocean for once-through cooling, with a maximum discharge of approximately 2.5 billion gallons per day, set by the facility’s Clean Water Act permit. PG&E closely monitors the marine environment at the plant by conducting regular studies and sampling, also required under the plant’s Clean Water Act permit.

PG&E relies fully on air cooling at two of our three natural gas power plants: Humboldt Bay Generating Station and Colusa Generating Station. At Gateway Generating Station, we use air cooling the majority of the time and use a small water cooling tower on hot days to assist in cooling for operations and power generation.

Additionally, PG&E owns and operates one of the nation’s largest investor-owned hydroelectric systems. Our hydroelectric power plants are largely non-consumptive, meaning that after water passes through turbines to produce electricity, it is returned to the river. In addition, PG&E’s 1,212 MW Helms Pumped Storage Project uses water for energy storage to help balance daily variations in electric demand.

Water conservation

PG&E’s offices and service centers rely on water for restrooms, kitchens, mechanical system cooling, vehicle washing, and landscape irrigation. We work to identify, report, and repair leaks quickly; manage our irrigation systems; install low-flow plumbing fixtures; and replace landscaping with drought-resistant approaches.  

We also deliver free wood mulch to homes and businesses to help them reduce water needed for plants and trees. 

2024 milestones

• Saw an increase in water usage at our offices and service centers, with overall consumption rising nearly 16% relative to the prior year. To mitigate this increase: 
  • We initiated xeriscaping projects at seven PG&E sites and upgraded PG&E’s design guidelines to include drought tolerant and native plantings, resulting in water savings.  
  • We continued to deploy a water management technology program at 27 different facilities. The program alerts facility managers about unusual water usage via real-time readings. Detected leaks are immediately repaired, and we investigate other high use cases to encourage conservation. 
  • We leveraged smart irrigation controllers, which use moisture sensors and weather data to decrease irrigation when not needed for landscaping. Together, these programs combined to save 8.5 million gallons of water in 2024.
• Helped customers save water. Altogether, customers who participated in PG&E’s programs reduced water usage by about 25 million gallons in 2024.
• Hosted the annual Water Conservation Showcase, which covered a range of topics with experts, nonprofits, universities, and other stakeholders. 
• Repurposed 80,000 gallons of water used in hydrostatic testing for beneficial reuse, including toward irrigation, dust suppression, and backfill compaction, as well as reseeding and watering disturbed areas to return them to their pre-project state. 

Measuring progress

1. Net operating capacity on December 31, 2024: Diablo Canyon: 2,240; Humboldt Bay Generating Station: 163 MW; Gateway Generating Station: 580 MW; Colusa Generating Station: 657 MW.  
2. The California Water Board adopted a policy in 2010 that generally requires power plants with once-through cooling (OTC) to install cooling towers or other significant measures to reduce marine impacts by at least 85%. Following passage of SB 846, which authorized the extension of Diablo Canyon Nuclear Power Plant operations beyond its current license period and allowed for an OTC exemption for the facility, Diablo Canyon will continue to operate its OTC system and pay an annual interim mitigation fee as required by the California Water Board policy until eventual plant retirement.
3. Freshwater sources consist of well water for backup and emergency purposes.
4. Diablo Canyon Power Plant’s water system was upgraded, and the site no longer uses well water to augment supplies of seawater for reverse osmosis. 
5. Water withdrawal data was significantly lower in 2022 due to an issue with the flowmeter from the water supplier. This issue has been resolved.
6. This represents data from office facilities and service centers for the 12 months from October to September. In 2024, 152 sites reported water data.
7. PG&E monitors water usage at permitted public water systems owned and operated by PG&E, including campgrounds and other recreational facilities. These systems are metered in accordance with state regulations. Nearly two-thirds of the total metered water withdrawal/usage by permitted systems in 2024 was comprised of remediation and process water used at the Hinkley Compressor Station.
8. These figures include once-through cooling discharge (equivalent to withdrawal amounts) plus estimated reverse osmosis system brine/backwash discharge.
9. Colusa Generating Station uses a zero-liquid discharge system. A septic system is used to manage sanitary waste.
10. In 2024, approximately 20% of the water used in hydrostatic testing was recycled or reused for irrigation, dust control, or project restoration.